Culvert pipes are widely used to allow water to flow beneath roads without having to redirect it or construct a bridge to pass over the stream. Unfortunately, such pipes represent an ideal place for beavers to construct a damn and restrict the flow of water. These damns can quickly cause flooding and washouts when water levels are elevated, for example, by heavy rains or melting snow. Vertical screens or grates have been used to prevent beavers from entering culverts, but such devices do not discourage beavers from building dams at the ends of a culvert pipe. Also, water flows tend to deposit debris at such barriers which builds up over time and restricts flow through the culvert.
U.S. Pat. Nos. 5,102,537 and 6,447,206 disclose cone-shaped screens that were intended to overcome the limitations of the flat designs discussed above. A base end of the screen attached to the end of the culvert has a series of rods extending outward from the culvert to an apex end. The rods are spaced by a distance that allows small debris to pass through without clogging the culvert while preventing entry by beavers and similarly sized animals. The beavers cannot construct an ideal damn at the opening of the culvert as they cannot properly anchor the structure.
As a result of limiting access to the culvert by beavers, the prior art also limits access to the culvert pipe by others. For example, it may be useful to connect other drainage systems, such as weeping tile, to existing culvert pipes. The combination of such systems is often ideal as it eliminates the need for separate piping systems and thus reduces cost and environmental interference. In addition, large culverts require correspondingly large screens that are difficult and costly to transport due to their dimensions. As a result, there is a desire for a beaver control device that is easy to transport and prevents dam construction and debris buildup at the end of a culvert pipe while allowing the connection of other drainage sources to the culvert.